Garmi ka Chaalan

Class 7 Science · Chapter 7: Prakriti mein Garmi ka Sthaanaantaran · NCERT Curiosity section 7.1

Seekho

Pahaadon ki thandi shaam Zoya aur Neel bua ke chulhe ke paas baithe, wo bade steel ke bhagone mein soup chala rahi. Neel bhagone mein rakhi steel ki karchhi chhoota aur jaldi chhod deta: "Ouch, hattha garam!" Paas ka lakdi ka chammach thanda. "Garmi karchhi par chadhi kaise?" Zoya poochhti.

Wo test karte: dhaatu ki patti par lagbhag 2 cm door chaar pin mom se chipkaao aur ek sira garam karo. Lau ke sabse paas ki pin pehle girti, phir agli, aise hi. Garmi garam hisse se thande hisse ki or jaati: har kan apni jagah chhode bina padosi ko garmi deta. Ye chaalan hai, thos mein garmi ka mukhya raasta.

Dhaatuein garmi ki achchhi chaalak, isliye bhagone aur tawe dhaatu ke. Lakdi, plastic, kaanch, mitti aur porcelain kharaab chaalak (kuchaalak): hatthe thande rehte aur kulhad ki chai der tak garam. Hawa bhi kharaab chaalak. Oonee kapde reshon mein hawa faslaate, aur beech mein hawa wale do patle kambal ek mote se zyaada garam rakhte.

Kaarigar ye vichaar use karte. Bahut thande pahaadi gaanvon mein deewaarein lakdi ki do parton ke beech mitti aur gobar bhari ho sakti, dono kuchaalak, to garmi andar rehti. Khokhli eentein hawa faslaakar ghar ko garmi mein thanda aur sardi mein garam rakhti.

Explore: kaunse padaarth garmi chalaate?

1. Har cheez jaanchkar sort karo.

Yaad rakho

• Chaalan: thos mein garmi kan se kan, garam se thande, kan bina hile.
• Dhaatuein achchhi chaalak; lakdi, plastic, mitti, kaanch, oon aur hawa kuchaalak.

Quick check

Kulhad mein chai steel ke gilaas se zyaada der garam kyun?

1. mitti garmi ki kharaab chaalak
2. mitti achchhi chaalak
3. steel chai thandi karta
4. mitti garmi jodti

Socho

Thandi subah pakshi pankh phula lete. Isse kya madad?

Practice

Teen levels (easy, medium, hard) ke naye sawaalon se practice karo, kuch hands-on, hints aur hal ke saath. Topic poora karne ke liye pichhle 5 mein se 4 sahi karo.